1. Field of the Invention
The present invention relates to transmission line cables that transmit high-frequency signals, and more particularly, to a transmission line cable including insulator layers stacked together.
2. Description of the Related Art
Various types of transmission lines that transmit high-frequency signals have been proposed. For example, International Publication No. 2014/069095 describes a transmission line having a strip line structure. International Publication No. 2014/069095 also describes a transmission line cable formed in a predetermined shape by electrically connecting a plurality of transmission lines.
FIG. 15 is a sectional view of a portion of a transmission line cable in which two transmission lines 140 and 240 are connected. The transmission line cable according to International Publication No. 2014/069095 is obtained by connecting the two transmission lines 140 and 240. The first transmission line 140 includes a first ground conductor pattern 121, a second ground conductor pattern, which does not appear in the sectional view of FIG. 15, and a first signal conductor pattern 130. The second transmission line 240 includes a third ground conductor pattern 221, a fourth ground conductor pattern 222, and a second signal conductor pattern 230. When the two transmission lines 140 and 240 are connected to each other, the first signal conductor pattern 130 and the second signal conductor pattern 230 are electrically connected to each other. In addition, the first ground conductor pattern 121 and the fourth ground conductor pattern 222 are electrically connected to each other.
In the structure illustrated in FIG. 15, the first ground conductor pattern 121 of the first transmission line 140 and the third ground conductor pattern 221 of the second transmission line 240 have a discontinuous portion between them, as indicated by the ellipse in FIG. 15. Therefore, there is a risk of unnecessary radiation from this section.